Compared to other seating devices, folding chairs offer the advantages of being compact and lightweight. Generally, folding chairs are easier to store and transport than are non-folding chairs. Further, folding chairs may often be purchased at a lower cost than non-folding chairs.
Typically, a folding chair consists of a seat, a backrest, and foldable support structures, including front and rear legs. When in an open position, the seat supports the weight of a person while the backrest provides support for the person's back, so the person may comfortably lean back while seated.
A problem with many folding chairs is that they sometimes inadvertently fold up while a person is sitting in the chair. For example, when a person seated in a folding chair attempts to slide the chair forward, such as toward a table, the legs of the chair may experience forces that tend to cause the legs to fold together. Also, in many types of folding chairs, if more weight is placed at the rear of the seat than is at the front of the seat, the chair has a tendency to fold up. In either situation, the person seated in the chair may become unbalanced and possibly fall, or at least may have to readjust the chair.
In addition to instability problems, many folding chairs do not fold into a flat and compact package. In most designs, the front and rear leg structures and seat cannot all collapse down into coplanar positions due to interference between the leg structures, or between the seat and the leg structures. The inability of many prior art chairs to fold flat makes such chairs difficult to stack. Also, when stacked, these chairs take up more space than would be used if they folded flat.
What is needed, therefore, is a folding chair that is stable and secure when unfolded and in use, and that folds into a flat, compact package for transport and storage.